This invention is concerned with fluid handling systems, such as, for example, reverse osmosis and hemodialysis systems in which it is required to monitor and control the flow rates of each of two merging fluid streams, a main stream and a secondary stream. In application, Ser. No. 590,897 filed June 25, 1975 and now abandoned in favor of application Ser. No. 687,133 filed May 17, 1976, there is described a system for handling two liquid streams which essentially consists in delivering volume of the first liquid to a chamber to fill that chamber, making a connection from that chamber a second and larger chamber and passing said determined volume of first liquid from the first chamber to the second chamber through said connection, a connection being made between a supply of second liquid and said connection between the two chambers so that the second liquid is induced into the second chamber in an amount equal to the difference in volumes between said chambers.
When that system is applied in a hemodialysis procedure, the source of second liquid is the dialysis cell and the second liquid comprises blood wastes, the blood wastes being drawn across the membrane of the cell by the negative pressure induced by the passage of the first liquid to the chamber of greater volume, the blood wastes being pulled across the cell in quantities equal to the difference in volumes of the two chambers.
In co-pending application Ser. No. 645,747 filed Dec. 31, 1975 there is described and illustrated another fluid handling system which comprises an hydraulic circuit with, in its simplest form, a receptacle, movable partition dividing the receptacle into first and second chambers, that partition being reciprocated within the receptacle to displace equal volumes in the two chambers. A conduit connects the two chambers and a source of a second liquid is connected to that conduit. In operation, first liquid is admitted to one chamber as that chamber expands and as that chamber contracts through reciprocation of the partition, that first liquid is passed through the conduit to the second chamber. Means are provided for removing liquid from the circuit so that second liquid is induced into the circuit in quantities equal to the amount of liquid removed through said liquid removal means.
The liquid removal means may consist of a simple outlet when the device is used in a dialysis system in which case liquid will pass through the outlet in quantities directly related to the quantity of blood waste migrating across the membrane of the cell or there may be provided a pump unit for removing predetermined quantities of liquid. Reference is made to said co-pending applications for a more detailed description of the inventions thereof.
The present invention is concerned with fluid handling systems of these general kinds.